During the last fifty years there has been a dramatic increase in the construction of tall multi-unit hotels, office buildings and residential complexes. Typically, these buildings are constructed with a concrete and steel framework. Accordingly, if a fire begins in a unit of a building, the fire can usually be contained to the particular unit or to a floor of the building. However, the spreading of toxic fumes within the building through ventilation systems, hallways and elevator shafts is a major problem for other persons within the building. Many synthetic materials used in upholstery and rugs (for example, polyurethane) give off toxic fumes upon combustion. Such fumes mixed with the ordinary smoke of combustion can choke, suffocate or poison other individuals in the building who are trapped and blinded by the smoke and unable to escape.
Frequently, the rooms of such buildings are sealed because of air conditioning and controlled atmosphere requirements, and often there is a pressure difference between the interior of the buildings and the outside atmosphere. Accordingly, persons within a unit trying to obtain a source of fresh air may find that the only way to get outside air is to break a window, but breaking a window can create a pressure drop in the room which could draw smoke and possibly fire from within the building to that particular unit to aggravate conditions there.
There have been numerous attempts in the prior art to provide air and oxygen supplies to persons trapped within such buildings. For example, U.S. Pat. No. 4,331,139 and U.S. Pat. No. 4,320,756 both present alternative designs of systems which might be used to supply air to a person trapped in a room in a burning building. Both of these patents attempt to utilize the air supply in the waste vents of a sewage pipe with a building. While these patents present a theoretical solution that may have practical merit in certain circumstances, the method proposed by the patents is not suitable for general application for there is a strong likelihood that the sewage system would become contaminated by toxic fumes and hot gases in the course of a fire. For example, the heat within the burning unit would soon evaporate the water from toilet fixtures and sink traps to allow the smoke and fumes to e drawn into the sewage pipes. Moreover, even if the sewer gas did not become contaminated by the smoke, the pipes could become heated by the fire to produce superheated gases which could burn the lungs of a person inhaling them. In any event, the gases ordinarily resident in the sewer system, while not fatally poisonous would likely cause some sickness if inhaled in quantity over a prolonged period of time.